1. Field of the Invention
The present invention relates to an image processing apparatus, an imaging apparatus, an image processing method, and a program which are applicable to a surveillance camera or the like.
2. Description of the Related Art
A technique is known for analyzing an input image of a camera to precisely detect a motion that has occurred in a screen (see Japanese Patent Laid-open No. 2006-79594, hereinafter referred to as Patent Document 1 for example).
According to the technique disclosed in Patent Document 1, with respect to each macroblock, images that are N frames apart from each other are compared with each other to calculate motion vectors, and with respect to each motion vector, temporal uniformity is determined to determine whether or not that motion vector belongs to a moving object. This achieves an increase in precision of motion detection information.
Also, a technique has been proposed for, for example, reducing a load on a monitoring system by use of detected motion information, as described below.
For example, a technique is known of alerting a surveillant in order to reduce a load on the surveillant.
Also, a technique has been proposed of decreasing a resolution of images to be transmitted when there is no motion, in other words, when there is no need for monitoring, in order to reduce a load on a network (see Japanese Patent Laid-open No. 2003-274390, hereinafter referred to as Patent Document 2 for example).
Also, a technique is known of omitting to record the images when there is no motion, in other words, when there is no need for monitoring, in order to reduce recording resources.
As described above, a variety of techniques have been proposed in recent years, and some of these techniques have already been put into practical use, such as in a field of surveillance cameras, for example.
Patent Document 2 has proposed a video distribution server and a video receiving client system which allow acquisition of video with a desired quality.
This system is configured to detect an unexpected occurrence in an area related to an object of photographing by an imaging apparatus, and control a compression ratio to allow an efficient use of a band of a transmission channel and acquisition of video with a desired quality while reducing a load on a user.
These techniques share the presupposition that absence of a motion in an area photographed by the surveillance camera is expectable during the photographing. On this presupposition, occurrence of even a few motions may be determined to be an abnormality.
For example, the aforementioned techniques and system will be effective for the purpose of monitoring areas where no motions are normally expected to occur, such as an inside of a vault without a human guard or a private land.